package com.fedorvlasov.lazylist;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.Collections;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import us.lithub.R;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.widget.ImageView;

public class ImageLoader {

	private MemoryCache memoryCache = new MemoryCache();
	private FileCache fileCache;
	private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
	private ExecutorService executorService; 
	private final int stub_id = R.drawable.stub;

	public ImageLoader(Context context){
		fileCache=new FileCache(context);
		executorService=Executors.newFixedThreadPool(5);
	}

	public void DisplayImage(String url, ImageView imageView) {
		imageViews.put(imageView, url);
		Bitmap bitmap = memoryCache.get(url);
		if(bitmap != null)
			imageView.setImageBitmap(bitmap);
		else {
			queuePhoto(url, imageView);
			imageView.setImageResource(stub_id);
		}
	}
	
	public void clearCache() {
		memoryCache.clear();
		fileCache.clear();
	}

	private void queuePhoto(String url, ImageView imageView) {
		PhotoToLoad p=new PhotoToLoad(url, imageView);
		executorService.submit(new PhotosLoader(p));
	}

	private Bitmap getBitmap(String url) {
		File f=fileCache.getFile(url);

		//from SD cache
		Bitmap b = decodeFile(f);
		if(b!=null)
			return b;

		//from web
		try {
			Bitmap bitmap=null;
			URL imageUrl = new URL(url);
			HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
			conn.setConnectTimeout(30000);
			conn.setReadTimeout(30000);
			conn.setInstanceFollowRedirects(true);
			InputStream is=conn.getInputStream();
			OutputStream os = new FileOutputStream(f);
			CopyStream(is, os);
			os.close();
			bitmap = decodeFile(f);
			return bitmap;
		} catch (Exception e){
			e.printStackTrace();
			return null;
		}
	}

	//decodes image and scales it to reduce memory consumption
	private Bitmap decodeFile(File f) {
		try {
			//decode image size
			BitmapFactory.Options o = new BitmapFactory.Options();
			o.inJustDecodeBounds = true;
			BitmapFactory.decodeStream(new FileInputStream(f),null,o);

			//Find the correct scale value. It should be the power of 2.
			final int REQUIRED_SIZE=70;
			int width_tmp=o.outWidth, height_tmp=o.outHeight;
			int scale=1;
			while(true) {
				if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
					break;
				width_tmp/=2;
				height_tmp/=2;
				scale*=2;
			}

			//decode with inSampleSize
			BitmapFactory.Options o2 = new BitmapFactory.Options();
			o2.inSampleSize=scale;
			return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
		} catch (FileNotFoundException e) {
			
		}
		return null;
	}

	//Task for the queue
	private class PhotoToLoad {
		public String url;
		public ImageView imageView;
		public PhotoToLoad(String u, ImageView i) {
			url=u; 
			imageView=i;
		}
	}

	private class PhotosLoader implements Runnable {
		PhotoToLoad photoToLoad;
		PhotosLoader(PhotoToLoad photoToLoad) {
			this.photoToLoad=photoToLoad;
		}

		@Override
		public void run() {
			if(imageViewReused(photoToLoad))
				return;
			Bitmap bmp=getBitmap(photoToLoad.url);
			memoryCache.put(photoToLoad.url, bmp);
			if(imageViewReused(photoToLoad))
				return;
			BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
			Activity a=(Activity)photoToLoad.imageView.getContext();
			a.runOnUiThread(bd);
		}
	}

	private boolean imageViewReused(PhotoToLoad photoToLoad) {
		String tag=imageViews.get(photoToLoad.imageView);
		if(tag==null || !tag.equals(photoToLoad.url))
			return true;
		return false;
	}

	//Used to display bitmap in the UI thread
	private class BitmapDisplayer implements Runnable {
		Bitmap bitmap;
		PhotoToLoad photoToLoad;
		public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
		public void run() {
			if(imageViewReused(photoToLoad))
				return;
			if(bitmap!=null)
				photoToLoad.imageView.setImageBitmap(bitmap);
			else
				photoToLoad.imageView.setImageResource(stub_id);
		}
	}

	private void CopyStream(InputStream is, OutputStream os) {
		final int buffer_size = 1024;
		try {
			byte[] bytes=new byte[buffer_size];
			while(true) {
				int count=is.read(bytes, 0, buffer_size);
				if(count==-1)
					break;
				os.write(bytes, 0, count);
			}
		} catch(Exception e) {

		}
	}
}